The present application claims benefit of the right of priority of Japanese Application No. 605995 entitled METHOD OF MANUFACTURING LARGE-SCALE CERAMICS BOARD, filed on Mar. 10, 2000.
The present invention relates generally to a method of manufacturing ceramics board and more particularly, to a method of improving production efficiency in manufacturing large-scale ceramics tiles and improving the quality of tiles.
One conventional method of producing tiles uses a small tile roughly divided into about twenty ceramics pottery tiles and a plastic tile. The small tile forms a fragment of a thin board for attaching on the wall. In Japan, it is usually called pottery product. In this method, the raw material is molded in small rectangles of 10xc3x9710 cm or 5xc3x9715 cm, and then the baked, for example, by the tunnel kiln.
Another conventional method uses comparatively recent technology of utilizing a large-scale ceramics tile, for example, covering an area of more than 1xc3x971 m. To manufacture the large-scale ceramics, a wet method process and roller press manufacturing methods have been used. Other methods, for example, described in U.S. Pat. No. 4,495,118, have the particle of the raw material in the line distribution in one direction to manufacture products of strong bend strength.
U.S. Pat. No. 4,495,118 describes a large scale ceramics board of a thin board, the size of which is about 30xc3x9730 cm, with about 20 mm or less thickness. The manufacturing method utilizes 15% moisture of the crushed raw material clay, feldspar, and the silica. The mixture is combined with kneading machine (pug mill) and are lined in one direction for distribution. As an extruder with curved, round or spiral exit brings rolled raw material clay, the clay is shaped to plate by partly cutting straight in the direction of axis. Next, with the roller type making arranged machine, thickness is evened and when molded again, it becomes like the board for an internal warp to be removed. Next, it is baked with the roller hearth kiln to obtain the product of large-scale ceramics board.
The method described, however, consumes a great deal of time and expense for constructing, producing uneconomical results. Moreover, the method described does not prevent the hygroscopic moisture such as the arrow-lined rain water which infiltrates easily in the building. Further, although extruder aligns crystal grain in raw clay in one direction, selection of raw material based on the shape of crystal grain is insufficient, and the bend strength of the product achieved by this method is still not enough. Therefore, because the size of 30xc3x9730 cm is considered as mid-sized for a large-scale thin board and because the thickness is 20-8 mm, it can be said that there still is a problem in the manufacturing method for large-scale thin boards which need improvement.
Further, the prior art rolling rollers have edges at both ends that are opened. When clay like cloth is expanded in a length-wise direction, unevenness in the orientation and density distribution occurs because the edges are open at the ends. Therefore, it is also highly desirable to have a rolling roller that reduces the tendency to cause unevenness in the product.
The present invention overcomes the shortcomings of the prior art and the difficulty associated with manufacturing large-scale sized ceramics tiles used in architectural material. The method of the present invention greatly improves production efficiency and plane degree during the manufacturing process. The ceramics tiles manufactured with the method of the present invention minimizes hygroscopic properties as to improve the sanitary qualities of the tiles and to reduce surface pollution. The ceramics tiles manufactured with the method of the present invention is made to be fireproof and is not subject to deteriorating from sun rays and harsh weather conditions.
The method of the present invention also improves the prior art methods of manufacturing the large-scale thin board ceramics tile by greatly reducing the tendency to crack easily that is so frequently associated with the large-scale thin boards. Drying raw board containing the argillaceous raw material, especially that of large area is likely to entail crack and transformation, and thus to prevent them, the prior art methods have utilized initial dehydration periods. Initial dehydration periods in the manufacturing method, however, leads to lower productivity.
The method in the present invention of manufacturing large ceramic thin board is an efficient method including a serial production achieved by improvements of the process in which distribution organization of raw material mineral is uniformly aligned. The present invention also provides improvement of existing burners such as the one described in U.S. Pat. No. 4,495,118. In one aspect of the present invention, the plasticity clay in the dry thing conversion 30-40%, wollstonite with needle crystal aspect ratio of more than 10 in an amount of 20-50% by weight, feldspar and/or talc having 10-50% by weight are uniformly crushed and mixed. A solution in an amount of 16-21% weight of this mixture is added to the mixture. The solution contains 10% paraffin emulsion solution. A clay-like composition of matter is extruded cylindrically with a vacuum kneading machine, which then is made into dough board compact of desired thickness after being partially cut parallel to that cylinder. Then the dough is heated to approximately 80 degrees Celsius with far infrared radiation. The dough is then put on heat proof metal mesh belt having temperature of 80 to 150 degrees Celsius. The heat is removed, and the dough is dried and desiccated, then baked at 1000-1200 degrees Celsius in a roller. In one aspect of the method of the present invention, the large-scale thin ceramics board is baked at the temperature of 1000-1200 degrees Celsius with roller hearth kiln combustion heating device.
Accordingly, the method includes pulverizing and uniformly mixing, in dry content conversion, plasticity clay in an amount of 30-40% by weight, wollastonite having an aspect ratio of more than 10 in an amount of 20-50% by weight, and feldspar and talc in an amount of 10-50% by weight to form a mixture; adding to the mixture a solution in an amount of 16-21% by weight of this mixture, the solution containing 10% by weight of paraffin emulsion; extruding clay-like composition to be formed cylindrical with a vacuum kneading machine; making the extruded clay-like composition into dough board compact of desired thickness after being partially cut parallel to that cylinder; heating the dough board compact to approximately 80 degrees Celsius with far infrared radiation, transporting the heated dough board on a heat proof metal mesh belt having temperature between 80 and 350 degrees Celsius; gradually heating and drying the heated dough board at 80 to 150 degrees Celsius to dehydrate the dough board; and baking the dehydrated bough board at 1000-1200 degrees Celsius in roller hearth kiln combustion heating device.
Another aspect of the present invention leaves space the thickness of the desire of the dough board up and down horizontally for the direction where the dough board rolled out progresses by the rolling roller and is composed. The interval of the upper and lower roller is gradually narrowed and at both ends the squeezing inclination is installed, and the width size of the cloth board is prevented from expanding.
Simultaneously, the hollow of the hemisphere of 0.2-0.3 mm is set in discontinuity on the surface of the roller. The method of manufacturing the large-scale thin ceramics board flakes off the roller and the dough board smoothly at the progress movement of the dough board.
Yet another aspect of the present invention include a method of heating the dough board compact. The dough board compact is heated in heating zone having alternately arrangedfar infared radiation body of 15 micrometers wavelength or less and far-infrared radiation body of 16 micrometers wavelength or more. Additionally, the method of manufacturing the large-scale ceramics board of the present invention includes material used for the heat proof metallic mesh belt which has the heat capacity about ten times the board of the cloth for each contact unit area compact. As described herein above, the cloth board compact is transported by the heat proof metallic mesh belt in the heating zone.
Further yet, one aspect of the present invention includes roller hearth kiln combustion heating to give an effect of radiant heat heating. The radiant heat is achieved by the black body heat radiation of the tube burner which in one embodiment comprises silicon carbide and silicon nitride qualities. The radiant heat is also achieved by far-infrared heat radiation. The tube burner has length which is 1.5 to 1.7 times the width of the material to be baked.